Filament spring structure



Jan. 5, 1932.

H. M. FREEMAN ET AL FILAMENT SPRING STRUCTURE Filed Jan. s, 1924 WITNESSES:

ATTORNEY Patented Jan. 5, 1932 PATENT orifice HUBERT M. FREEMAN AND LEE SUTI-IERLIN, 0F EAST PITTSBURGH, PENNSYLVANIA, ASSIGNORS T0 WESTINGHOUSE ELECTRIC AND MANUFACTURING COMPNY, A

CORPORATION 0F PENNSYLVANIA FILAIVIENT SPRING STRUCTURE',

Application i'iled January 8, 192,4. Serial No. 684,985.

This invention relates to vacuum tube devices.

It is an object of our invention to render vacuum tubes less microphonic.

It is a further object of this invention to provide a supplementary holding device for the upper end of the filament which shall prevent sidewise motion thereof.

It is a further object of this invention to provide filament holding means of such form as to frictionally oppose longitudinal movement of the upper end of the filament and thereby damp vibrations of the lament.

It is a further object of this invention to prevent vibration of the usual supporting spring in one direction and to damp vibration thereof in a direction perpendicular thereto.

Other objects of the invention and detailsY of the construction will be evident from the following description and the accompanying drawings in which:

Figure l is a view of the interior parts of a vacuum tube device with our invention applied thereto,

Fig. 2 is an enlarged perspective'view of one form of damping device.

Fig. 3 is a similar view of another form of damping device, and

Fig. 4 is a similar view of still another modification. Y

A vacuum tube of familiar construction has a press 1- provided with standards 2 for supporting the plate, the grid and the lower end of the lament in the usual way. The press is also equipped with a standard 3 for supporting the upper end of the filament.

A spring 4 is secured at one end to the standard 3 and, at the other end, to a connector 5, which is attached to the upper end of the filament. Preferably, the connector is welded both to the filament and to the spring, but any suitable fastening may be used.

A holding or damping device comprises a member 6 of U-shape secured to the standard 3 as shown at 7. Preferably, the member 6 is made of nickel or other soft metal capable of withstanding a high temperature. The arms 8 of the U-shape holding device extend on each side of the spring 4 as shown in Fig.

`- 4 andthus afford ample 2. Thesearms may be slightly converging', so that only their free ends Contact with the edges of the spring 4. yThey may, instead, if desired, be so bent as to engage the spring along a substantial portion of the lengt-h of the arms. 8 and the spring4 should be firm enough to afford friction when the spring moves, but should not be tight enough to kprevent the spring from moving vertically.

In the form shown in Fig. 2, the holding device is made of a comparatively' thick rectangular bar, affording ample surface for welding tothe standard 3, and suiiicient bearing surfaces for engaging the edges of the spring 4. f

In the form shown in Fig. 3, a wire 9 is used instead Lof a bar. It is welded at v l() to the standard, somewhat below the point of attachment of the spring 4. The ends of the bar are turned through a right angle so as to extend upwardly as shown at 11. These upturned ends engage the edges of the spring frictional surface for damping the vertical movement of the spring. Obviously, if the wire member be reversed, the weld 6 will be above the spring and the endslS will extend downward.-

In, the form shown in Fig. 4, the U-shape member is madeA of iiat ribbon which is narrower-than that shown in Fig. 2. Instead of Yengaging the spring, the ends of the ribbon engage the connector 5. In this form, therefore, the provision for friction during the vertical movement vof the spring is obtained without requiring vertical surfaces of any considerable extent on the U-shape member. In-the operation of the device, horizontal movements of the spring 4, and, therefore, of the upper end of the filament are prevented by the presence of the arms of the guiding device. Vertical vibration of the spring can, however,takeplace. Thus, a whipping action of the filament accompanied by a vertical movement of its upper end, is permitted. This arrangement prevents strains on the filament which might otherwise break it.

The vertical movement of the upper end of the filament and, therefore, the whipping actioniis, however, quickly damped by the The engagment between the arms friction between the spring and the guide in the forms shown in Figs. 2 and 3 or between the connector and the guide in the form shown in Fig. 4:. In each case, therefore,

friction effecting damping is provided somewhere in the supporting system which connects the upper end of the lament to the standard 3.

Although the invention has been illus'- trated and described in connection with a ilament which is spring-supported at its upper end, it will be obvious that it can Ybe applied to a spring support located at any other point.

15 Many modifications of the details of the structure will occur to those skilled in the art. W e do not, therefore, intend that the specific illustrations chosen shall be interpreted as a limitation. No limitation is in- 2@ tended except which is necessitated by the prior art or indicated in the claims.

We claim as our invention: 1. A non-microphonic vac-uum tube comprising a filament, a standard, a spring sen.; cured to said standard, a connector at the upper end of said iilament secured to said spring, said spring and connector constituting a supporting system uniting said standard and said filament, and a member having 3G a hairpin-shape portion secured to said post and extending along each side of said spring, said member frictionally engaging said supporting system to such degree as to damp longitudinal motions of the filament.

35 2. In a non-microphonic vacuum tube device, a standard, a spring welded to said standard and extending at substantially a I right angle thereto, a filament, a filament connector securing said filament to said 4G spring at a point remote from said standard,

a member of nickel including a hairpin-shape part embracing said standard and Welded thereto, said nickel member extendingv along each side of said spring and frictionally ena5 gaging the same on each longitudinal edge.

In testimony whereof, we have hereunto subscribed our names this V17th day of December, 1923. HUBERT M. FREEMAN. 5o LEE SUTHERLIN. 

